The Right Chemistry: Processed foods have many faces

The cruise ship had a restaurant dedicated to “molecular gastronomy,” so of course I was eager to try it. I was familiar with the term. It had been introduced just a few years earlier in 1988 by French chemist Hervé This and Hungarian physicist Nicholas Kurti to describe a discipline that “seeks to generate new knowledge on the basis of the chemistry and physics behind culinary processes.”

The duo was not the first to explore the science of cooking. As early as 1825, French lawyer Jean Anthelme Brillat-Savarin composed a book called The Physiology of Taste, described as a gathering of “the intelligent knowledge of whatever concerns man’s nourishment.” In 1847, Justus von Liebig, one of the greatest organic chemists of the 19th century, published Researches on the Chemistry of Food in which he — as it later turned, out erroneously — argued that cooks should sear meat to retain its fluids. Then in 1984, Harold McGee published his masterpiece On Food and Cooking: The Science and Lore of the Kitchen, in which he discusses in detail where our foods come from, their chemical composition, and how cooking changes their chemistry.

While I have thumbed McGee’s book until the pages have become ragged, my interest in the chemistry of cooking traces to another book published earlier: The Cookbook Decoder, or Culinary Alchemy Explained by Dr. Arthur E. Grosser. Grosser had been my physical chemistry professor at McGill University, so of course I was interested in reading his book. In a witty fashion, he talks about puncturing an eggshell with a pin to prevent the horror of a hard-boiled egg with a flat bottom, and why cloves of garlic should be mashed before adding them to a dish. That’s because two chemicals have to combine to create allicin, the compound responsible for the flavour of garlic, and that only happens when cell membranes break.

Hervé This and Kurti went one step further than just discussing the chemistry of cooking — they introduced the idea of “molecular cuisine” to explore novel culinary methods rooted in science. It was a couple of those “novel methods” I experienced dining in the cruise ship’s avant-garde restaurant. The first item, served in a test tube, consisted of beads that popped in the mouth to release an orange flavour. This was an example of “spherification,” one of the most common techniques in “molecular cookery.” From having read This’s book, I knew the chemistry involved. When orange juice is mixed with calcium chloride and added one drop at a time to a solution of sodium alginate extracted from brown seaweed, a thin membrane of calcium alginate forms, trapping the orange juice in pearl-like beads.

This “appetizer” was followed by a soup that was essentially a flavoured foam. I’m not sure how that was prepared, but the usual method is to whip a liquid, in this case a soup base, with a hand mixer until it forms a foam that is then stabilized by the addition of the emulsifier lecithin, extracted from soybeans. The foam dissolves in the mouth, bathing the taste buds in flavour before it vanishes into thin air.

All in all, the encounter with chemistry in this setting was enchanting, but the gustatory merit of the experience was questionable. However, what was not questionable was that the meal was composed of highly processed foods. And that is what now sparked this decades-old recollection of my fling with molecular gastronomy. Today, the scientific and popular literature scream about how “ultra-processed” foods are wreaking havoc with our health. But like just about every nutritional issue, the science is nuanced.

Unless we are talking about an apple picked off a tree, or a tomato plucked off a vine, our diet consists of processed foods. Cooking is a process, as is pickling, drying or freezing. Blending oil with vinegar and adding egg yolk as an emulsifier to make mayonnaise is a process, as is tenderizing a steak with pineapple juice. But what do we mean by “ultra-processed” foods?

A simple definition is elusive, but akin to pornography: You know it when you see it. A common description is that a food is deemed to be ultra-processed if it has more than one ingredient that you rarely find in a kitchen and is commonly packaged in a container that has a label with a list of ingredients such as preservatives, emulsifiers, sweeteners, artificial colours and flavours that are not typically used in home cooking. Also, ultra-processing may include high pressure hydrogenation of fats, hydrolyzing vegetable proteins with acids and the use of extrusion equipment to produce cereals. Cold cuts, potato chips, breakfast cereals, frozen pizzas, instant soups, commercial ice cream, flavoured yogurt, plant-based meat substitutes, mass-produced packaged bread, chicken nuggets and French fries would fall into the ultra-processed category.

Roughly 60 per cent of the western diet is made up of ultra-processed foods. So what? Unfortunately, numerous studies have linked the consumption of these foods with an increased risk of cardiovascular disease, cancer, Type 2 diabetes, and obesity. Although an association cannot prove a cause-and-effect relationship, attention is warranted when so many studies all point in the same direction.

The prevailing opinion has been that the negative effects of ultra-processed foods are due to their high content of sugar, fat and salt. However, an epic clinical trial by Dr. Kevin Hall of the National Institute of Diabetes and Digestive and Kidney Diseases, which had subjects eat ultra-processed food for two weeks and then unprocessed food for two weeks, revealed that there was more to the issue. The participants were allowed to eat as much as they liked of the meals, both of which contained the same amount of sugar, salt, fibre and fat. Yet the subjects on the ultra-processed diet ate about 500 calories a day more and put on about 0.9 kilograms while the other group lost about the same amount. Since both diets were judged to be equally palatable, some other factor is involved.

One possibility is that ultra-processed foods have their structure altered by whatever processing they undergo, making them softer so that they can be consumed faster. More calories are consumed per minute, meaning that a feeling of fullness is delayed until long after the food has been consumed. “Protein leverage” is another possible issue. We seem to have a biological need to consume a certain amount of protein a day, and ultra-processed foods are generally lower in protein, prompting greater consumption.

As far as a link to disease, additives such as emulsifiers and sweeteners may change the composition of the gut microbiome, reducing the bacteria that produce short chain fatty acids that can keep inflammation in check. For whatever reason, it is becoming more and more clear that ultra-processed foods have a negative effect on health and that home cooking is the way to go.

Finally, I don’t think I was in any way harmed by the lecithin-laden spherical beads served in a test tube, but as much as I like chemistry, I don’t think you need chemical gimmicks to serve good food.